1. Field of the Invention
This invention relates to a method for treating Downstream systems and equipment, used in the transportation and storage of formation fluids produced from oil and gas wells with chemicals useful for reducing corrosion, scale, asphaltenes and other undesirable conditions. This invention particularly relates to a method for the controlled placement and release of such chemicals.
2. Background of the Art
Fluids produced from oil wells primarily include crude oil and water and is herein referred to as formation fluid. A formation fluid may also contain natural gas which may or may not be desirable and may be the primary product of a given well in which case the well is sometimes referred to as a gas well. A formation fluid may also contain CO2 and will often contain oil and water insoluble compounds such as clay, silica, waxes, and asphaltenes, which exist as colloidal suspensions. In addition to the already listed components, formation fluids can include inorganic components that can precipitate to form mineral scales.
It is known in the art of oil and gas production to eliminate or mitigate the effects these undesirable materials. For example, during oil and gas production in production wells, the drilling of new wells, or workovers of existing wells, many chemicals, referred herein as “additives”, which include scale inhibitors, paraffin inhibitors, corrosion inhibitors and the like, are often injected from a surface source into the wells to treat the formation fluids flowing through such wells to prevent or control the precipitation of mineral scale, paraffins, and to protect the well against corrosion. 
In addition to oil wells, there are other systems and equipment used for oil and gas exploration and production that may come into contact with formation fluids. For example, some equipment may be used to separate, at least partially, an aqueous phase from a hydrocarbon phase. Other equipment may be used to eliminate excess water from a gas phase of a formation fluid. The formation fluid is often transported to a refinery or other location where it is refined or otherwise treated in order to prepare it for marketing. Any or all of these systems may be exposed directly to formation fluid, and as a result be subject to the same problems as described for oil and gas wells.
Supplying additives in the form of emulsions and solutions can also be an expense. Solutions and emulsions are, by their natures, composed of mostly inactive materials: water and/or solvents. It would be desirable in the art of treating systems and equipment used to produce oil and gas to supply additives in a form that is economical to ship and handle and does not require co-shipping inactive components.
While using solid additives would seem to be a good means of avoiding the problems associated with additive solutions and emulsions, it too is not without problems. One such problem is metering solids. The metering of solids may be both expensive and prone to blockages and other conditions requiring maintenance. One solution to this problem is disclosed in U.S. Pat. No. 6,326,335 B1, to Kowlaski, et al. Therein it is disclosed to prepare a microencapsulated additive wherein the additive is incorporated into a gelatin capsule, weighted with a heavy metal compound.
It would be desirable in the art of treating systems and equipment used in the exploration for and production of oil and gas with additives, to use solid additives that would release slowly with time. It would be particularly desirable to use solid additives that would not require heavy metals as weighting agents. It would also be particularly desirable in the art to locate the additives at the point that requires the treatment for which the additives are used.